Suomi NPP CrIS SDR Provisional Product Highlight Yong Han, CrIS SDR Team Lead Suomi NPP SDR Product Review NOAA Center for Weather and Climate Prediction (NCWCP) 5830 University Research Park, College Park, Maryland October , 2012

Outlines Team Membership CrIS operational concept Beta product and issues SDR specifications Highlights and caveats of the current product (Provisional) Lessons learned Summary 2

CrIS SDR Team 3JPSS DPA Program Planning PI NameOrganization Funding Agency FY13 Task Yong HanNOAA/STARNJOSupport NPP/J1 Calval Deron ScottSDLNJOSupport NPP/J1 Calval Hank RevercombUWNJOSupport NPP/J1 Calval Larrabee StrowUMBCNJOSupport NPP/J1 Calval Dan MooneyMIT/LLNJOSupport NPP/J1 Calval Neal BakerDPANJOSupport NPP/J1 Calval Dave JohnsonNASA Support NPP/J1 Calval Joe PredinaExelisNASA/NJOSupport NPP/J1 Calval Degui GuNGASNASASupport NPP/J1 Calval & transition Wael IbrahimRaytheonNASASupport NPP/J1 Calval

CrIS Operational Concept 2,200 km Swath Downlink NWP, EDR Applications Decode Spacecraft Data ±50° Cross track Scans 3x3 Array of CrIS FOVs (Each at 14-km Diameter) Ground Station RDR = Raw Data Record SDR = Sensor Data Record EDR = Environmental Data Record 30 Earth Scenes RDRs EDRs Co-Located ATMS SDRs Global Temperature, Moisture, Pressure Profiles CrIS on NPP RDRs Interferograms Calibrated / Geolocated Spectra SDRs CrIS SDR Algorithm

Pre-Process RDR FFT to spectrum FCE handling Non- linearity correction Radiometric Calibration Spectral resampling to user grid Self- apodization removal Geolocation RDRs: Interferograms 8 sec science Telemetry 4 min Engineering packet Geometric data SDR Residual ILS removal Post calibration filter Spectral calibration Radiometric calibration All calibration coefficients and parameters are included in the Engineering packet

CrIS CalVal Activity Category Early sensor checkout and optimization (EOC, completed) CrIS performance characterization (EOC, ICV) SDR software update and algorithm improvement (EOC, ICV, LTM) Radiometric calval – NEdN, nonlinearity, ICT model and etc (EOC, ICV, LTM) Spectral calibration calval (EOC, ICV, LTM) Geolocation calval (EOC, ICV, LTM) CrIS performance trending and monitoring (EOC, ICV, LTM) 46 CalVal tasks are detailed in the CalVal plan 6 EOC – Early Orbit Checkout (completed) ICV – Intensive Calibration and Validation LTM – Long Term Monitoring

Beta Product Declared on May 15 Major Efforts resulted in CrIS SDR Beta product – Instrument checkout: PGA setting and bit trim mask updates (Engineering packet v32, uploaded on Feb. 8) – Spectral and Radiometric CalVal: ILS parameters, nonlinearity coefficients and ICT emissivity table updates (Engineering packet v33, uploaded on April 11) – Data quality assessment and data analysis: new onboard FIR filter (uploaded on April 18) to remove sweep direction dependent radiance bias – Critical SDR software bug fixes Issues – Data quality flag errors: ~60% of good SDRs are flagged as Degraded – Missing and corrupted RDR packets are not handled appropriately under certain conditions – The fringe count error (FCE) detection and correction code module is defective and has been turned off, as the FCE is currently a rare event Caveats described in the Beta Readme file – The data quality flags are defective – The fringe count error (FCE) detection and correction module was turned off – Monitored laser wavelength is set to zero – Some scans are incorrectly wrapped into granules whose time stamps don’t match 7

CalVal Activities since Beta Review Meeting Spectral and radiometric uncertainty characterization – Inter-satellite/sensor comparisons – Observation vs. radiative transfer model comparisons – Gain analysis: orbital dependence, channeling, stability – Internal consistency check: FOV-2-FOV comparisons, FOR-2-FOR comparisons, component correlation analysis and PCA – Calibration algorithm analysis: spectral ringing and proposal for improvement – Full resolution data analysis for SW spectral calibration Geolocation validation – Uncertainty estimated using VIIRS data and near coastline CrIS data; 4.5 km error was found and fixed Algorithm improvement and code fix – New data quality flag based on imaginary part of radiances – New algorithm for checking temperature limits – Engineering packet updates from v33 to v34 and v35 – Code fixes for geolocation and handling missing packets 8

NPP CrIS Sensor Data Record Calibration Uncertainty Specifications BandSpectral range (cm -1 ) N. of chan. Resolution (cm -1 ) FORs per Scan FOVs per FOR BB mW/m 2 /sr/ cm -1 Radiometric BB (%) Spectral (chan center) uncertainty ppm Geolocation uncertainty km LW MW SW SDR Calibration Uncertainty Radiometric uncertainty specification converted to that expressed in brightness temperature

Highlights of the Current CrIS SDRs (Provisional)

NEdN 11 Feb 1 Mar 2 May 2 Jun 4 Jul 4 Aug 6 NEdN The noise levels are much better than the specification The large NEdN at MW FOV 7 is a known issue before NPP launch NEdN at selected wavenumber ranges Stable NEdN over 8 months

Spectral Uncertainty 12 Longwave band, cm -1 Midwave band, cm -1 Shortwave band, cm -1 Inter-FOV spectral shifts relative to FOV5 derived from correlation analysis Longwave band Midwave band ppm Spectral shifts assessed with RTM LW & MW band frequency uncertainty < 3 ppm (specification 10 ppm) SW band frequency uncertainty relative to FOV5 < 3 ppm

Radiometric Uncertainty Assessment Inter-FOV difference 13 LW, cm -1, wrt FOV5 LW, cm -1, wrt FOV5 MW, cm -1, wrt FOV9 MW, cm -1, wrt FOV9 SW, cm -1, wrt FOV5 SW, cm -1, wrt FOV5 BT Diff (K) FOV-2-FOV differences are less than 0.04 K for LW and MW and less than 0.1 K for SW

Radiometric Uncertainty Assessment Daily Mean CrIS-AIRS Differences 14 Stable difference ~0.1 K v33 upload Mar Oct

Radiometric Uncertainty Assessment CrIS-IASI SNO (North Pole) 15 Sample size = 411 CrIS - IASI CrIS IASI The CrIS IASI difference is ~ 0.2 K

Radiometric Uncertainty Assessment Time-Series of GEO-LEO Tb Difference Similar CrIS-GOES, AIRS-GOES and IASI-GOES differences 16

17 Radiometric Uncertainty Assessment CrIS/VIIRS (M13 4um) comparisons Difference is less than 0.2 K

Standard deviations of Biases vs Radiative Transfer Model (RTM) simulated radiances Radiometric Uncertainty Assessment Radiance Bias Estimated with RTM Overall bias < 0.2 K FOV-2-FOV differences < 0.1 K 18 Standard deviation (over 9-FOVs) of Bias vs RTM simulated radiances Bias (K)

Co-located VIIRS IR data are used to estimate the CrIS geolocation uncertainty A coding error was found that caused the geolocation error 19 Geolocation Uncertainty Assessed with VIIRS Geolocation uncertainty within 30 o scan angles < 1 km (specification 1.5 km) IDPS MX km geolocation error error CrIS - VIIRS IDPS MX6.3 CrIS image Bias (m) RMSE (m) Track-2180 Scan-864 VIIRS geolocation uncertainty Image differences (CrIS – VIIRS) before and after a coding error fix

Overall Quality Flag Improvement 20 Quality flag: Blue color – GOOD Green color - DEGRADED Beta product Current product Engineering packet v34 uploaded Percentage (%) A false alarm (data labeled as Degraded) was fixed with code changes and parameter updates Will be fixed with uploading Engpkt v35 on Oct. 22, 2012

New Quality Flag Based on Imaginary Radiance Good radiance spectra have near zero imaginary radiances Add a bit flag to indicate the spectrum is Invalid if any imaginary channel in the range exceeds the thresholds: – LW: upper limit 1.5, lower limit -1.5, in the range 800 – 980 cm -1 – MW: upper limit 0.5, lower limit -0.5, in the range 1500 – 1700 cm -1 – SW: upper limit 0.05, lower limit -0.05, in the range 2250 – 2350 cm Hit threshold to make the bit flag turned on Range of interest Invalid spectrum example This is an important QC algorithm for detecting invalid SDR data caused by FCE events and many other RDR problems

Issue under Investigation SW Cold Scene FOV Differences 22 Brightness temperature averaged over the range from 2256 to 2302 cm -1 ; the scene is very cold

Issue under Investigation Ringing at the End of Un-apodized Spectra 23 Differences in NWP biases with interferometer scan direction Difference between IDPS and MIT/LL SDRs External apodization (e.g. Hamming) is recommended that can reduce the ringing to a level below 0.1 K

Status of Discrepancy Report (DR) Total 87 CrIS SDR DRs on CasoNOSA 72 DRs closed 16 DRs still open – none is critical for the Provisional – 4 DRs (#3563, #4937, #4661, #4232) are being closed – 2 FCE-related DRs (#4508, #4481) will be fixed in future together with the algorithm fix FCE even has been rare so far A new QC algorithm has been implemented, which is able to flag the data as Invalid If FCE happens – 5 DRs (#3081, #4198, #4253, #4774, #4812, #4407) will be handled in the future (DPA agrees) No significant impact on the Provisional product users – 3 DRs (#4391, #4389) are minor code issues and will be fixed for Validated product no significant impact on the Provisional product users – 2 DRs (#4868, #4090) will be fixed in Mx6.5 and Mx7.0 Once a month the IDPS will generate a bad scan of SDRs from a good scan of RDRs Currently the data are correctly labeled as Invalid 24

Issues and Provisional Product Caveats Issues – Software issues are still appearing – Significant SW cold scene FOV differences – Spectral ringing – FCE module currently turned off – Several potential software components need to be checked out (e.g. the process of triggering CMO calculation by metrology laser variations has not been verified) Provisional product caveats – The value of the ESZPDMMagnitude field may not be corrected due to an inconsistency between the internal data types (DR 4389); the error will be fixed in the next build – The fourth scan of the SDR granule generated from a short RDR granule (3 scans) is not valid (filled with fillvalue), but labeled as Valid; will be fixed in Mx6.5 25

Path Forward Suomi NPP – Continuation of CalVal as planned for the remaining ICV and LTM – Fine adjustment of spectral and radiometric calibration parameters and geolocation mapping parameters – Algorithm and software quality control improvements (FCE detection/correction, self- apodization correction and code fix) – Close of all remaining and new DRs – Aircraft campaigns – Documentation, including SDR product user guide – Algorithm and code enhancement for handling full resolution RDRs – SDR Validated product: June 2013 JPSS J1 – Support of and participation in pre-launch testing and instrument characterization – Algorithm and software improvement (calibration algorithm, full resolution SDR and computation efficiency) 26

Lessons Learned Inadequate pre-launch software and algorithm testing resulted in a number of critical post-launch problems ADL is not fully compatible with IDPS, which caused delays of CalVal fixes, as the team had to wait for results from IDPS, which was not updated as often as the team wanted 27

Summary CrIS SDR has reached the Provisional maturity level All critical DRs and document issues have been addressed A number of CalVal and software issues have been identified and will be addressed for the Validated product The team has a clear path moving forward for both NPP and J1 missions 28 Calibration type Meet Specification LW bandMW bandSW band NEdN Radiometric calibration Spectral calibration * Geolocation ** * Relative to FOV5 ** Within 30 o scan angles

CrIS SDR Status at Provisional Maturity Level 29 Provisional Maturity Level DefinitionStatus Ready for operational evaluation True Product quality may not be optimal True Incremental product improvements are still occurring as calibration parameters are adjusted True Version control is in affect True General research community is encouraged to participate in the QA True Users are urged to consult the SDR product status documents prior to use of the data in publications True